Descending into spicy

Just recently finished adding multiple dungeon levels that can be traversed in both directions by using the stairs.  Got a little bit carried away and implemented a full system for specifying a branch of arbitrary depth, which took a while longer than I initially planned. Going up in the staircase on the first level is still the win condition for the moment. Next step is to add a gating item so that the victory exit can't be accessed so easily...